The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 22, 1986
Filed:
Nov. 15, 1984
Keiro Shinkawa, Yokohama, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
In an FM demodulator of the phase locked loop system wherein a closed loop is formed by a phase detector, an amplifier, a loop filter, and a voltage controlled oscillator, a part of the amplifier is formed by a differential amplifying circuit which has a constant current source and is driven by a constant current. The center frequency of the frequency demodulation slope of the constant current source is changed by changing the current from the constant current source in response to the signal which was frequency demodulated by the phase locked loop. Further, a low-pass filter having the pass band of the frequency band of the signal to be modulated is provided in the path of the system from the differential amplifying circuit to the constant current source.